This disclosure relates to servicing a wellbore. More specifically, it relates to servicing a wellbore with fluids comprising cement kiln dust (CKD), an organic acid, and water.
Natural resources such as gas, oil, and water residing in a subterranean formation or zone are usually recovered by drilling a wellbore down to the subterranean formation while circulating a drilling fluid in the wellbore. After terminating the circulation of the drilling fluid, a string of pipe (e.g., casing) is run in the wellbore. The drilling fluid is then usually circulated downward through the interior of the pipe and upward through the annulus, which is located between the exterior of the pipe and the walls of the wellbore. Next, a train of fluids, including a spacer or an efficiency fluid, can be placed though the interior of the pipe and upward into the annulus to displace a portion of the existing fluid in the annulus, in order to separate the drilling fluid from the cementing fluid and prepare the wellbore to receive the cementing fluid. After that, primary cementing is typically performed whereby a cement slurry is placed in the annulus and permitted to set into a hard mass (i.e., sheath) to thereby attach the string of pipe to the walls of the wellbore and seal the annulus. Subsequent secondary cementing operations may also be performed.
Cement kiln dust, or CKD, is a material that can be included in wellbore servicing fluids such as spacer fluids or cementitious fluids. For example, CKD can be used to increase the strength development of Portland cements or as a pozzolanic type material in cementitious compositions. Although the use of CKD is fairly common, there are some inherent challenges associated with CKD such as source to source variability in composition and performance properties. Of the variations possible with different CKDs, one potential issue relates to their differing gelation behaviors. For example, a CKD from one source may not gel at all when mixed with water, while another may gel strongly. Therefore, there exists a need to address mitigation of this variable CKD gelation during wellbore servicing operations such as cementing to increase service quality, improve flowability (pumpability) of fluids comprising CKD, mitigate risks of premature end of job due to gelation-associated problems, and to address other issues related to CKD gelation.